This invention relates to the field of remote terminals as used in wireline telephony, and, more specifically, to a call control system for use with a remote terminal to move routing of emergency or other special telephone calls closer to the calling telephone and thus improving connection time.
Wireline telephone local exchange carriers use remote terminals (such as, but not limited to, subscriber loop carriers and digital loop carriers) to serve customer telephones that are too far from the nearest local switching office to provide acceptable service directly. A remote terminal is connected to a local switching office by one or more trunk groups, which provide voice paths and a control path between the local switching office and the remote terminal. The local switching office controls the remote terminal as if it were merely an extension of the switching office. There is no local controller or switch fabric in a remote terminal to save on cost, complexity and space. In this manner, subscribers that otherwise could not be served by conventional wireline telephony can be served by a remote terminal. Further, the telephone local exchange carrier does not have to build or buy expensive local switching offices or remote switching modules to serve only a few subscribers.
A problem in the art, however, is that call completion can be delayed because control of the remote terminal is tightly coupled to the local switching office. A remote terminal is deemed to be “tightly coupled” to the local switching office because the local switching office performs all of the telephony functions, such as (but not limited to) digit collection, translations, routing decisions, etc., for every call from every remote terminal connected to it. It is known in the art that call completions are slowed by concentration in the line unit, transmission conversions, the transmission itself and the reconversion at the local switching office. The round trip from remote terminal to local switching office to remote terminal also introduces some delay.
For most purposes, such delay is minimal and not noticed by the consumer. Certain classes of calls, however, are affected more than others. These calls are generally known in the art as “special number” calls. Examples of special number calls include, but are not limited to, operator, international operator, international calls, information and, importantly, emergency services calls (herein “9-1-1 calls”).
It is well known in the art that, if a caller to 9-1-1 is not connected to a public safety answering point operator with ten seconds, the caller is likely to end the call and call again. Repetitive 9-1-1 calls only increase delay, because call resources in both the local switching office and the remote terminal have to be torn down and reallocated by the local switching office for every call. If the remote terminal, the local switching office, or both, are busy, then there is also a possibility that a 9-1-1 call may not get through at all because of lack of resources.
Thus, there is a need in the art for a system that can expedite 9-1-1 and other special calls from a remote terminal to the public safety answering point.